The need for radiation detecting materials has been at the forefront of materials research in recent years due to applications in national security, medical imaging, X-ray detection, oil well logging, and high-energy physics. Essential qualities that a scintillator must possess are high light yields, fast luminescence decay (below 1000 ns), good stopping power, high density, good energy resolution, ease of growth, proportionality, and stability under ambient conditions. LaxBr3:Ce1-x (E. V. D. van Loef et al, Appl. Phys. Lett., 2001, 79, 1573) and SrxI2:Eu1-x (N. Cherepy et al, Appl. Phys. Lett. 2007, 92, 083508) are present day benchmark materials that satisfy some of the desired criteria, but their application is limited due to the extreme hygroscopic nature.
Barium mixed halides, such as barium fluoride iodide (BaFI) doped with Eu, have been studied as a photostimulable phosphor since the mid 1980's for applications in computed radiology (K. Takahashi et al, J. Electrochem. Soc, 1985, 132, 1492). However, none of these have been identified as candidate scintillators for detecting gamma rays.